The investigation which has led to recent discoveries in this cemetery had not been completed when De Rossi identified the Cœmeterium Ostrianum (of which we spoke above) as the scene of S. Peter’s work. It is these latest “finds” that have induced Marucchi to fix the Priscilla Cemetery as the place where the great apostle laboured in those early years of the history of Roman Christianity.
Beneath the first vast gallery of this catacomb with its many memories of saints and martyrs, including the famous crypt of the “Acilii Glabriones” house, lies another and very ancient area of sepulchral galleries.
This area was communicated with by several staircases, some of which are now completely closed. This vast sepulchral area has been as yet only partially explored. It is described roughly as consisting of a long gallery, out of which lead more than twenty other galleries, many of which as yet are only imperfectly investigated.
Marucchi, who has devoted a long and important section of his great work to the Priscilla Catacomb, writes of this second story of the cemetery as the most extensive and carefully planned of all the cemeteries of subterranean Rome that have been yet examined.
His words here are remarkable, and must be quoted: “On peut dire sans exaggeration, que c’est la région cemétériale la plus vaste et la plus régulière de toute la Rome souterraine.”
The masonry used in its construction; its many inscriptions on the loculi, carved in marble, or painted in red on tiles,—all bear witness of its hoar antiquity; much of it dates certainly from the second century. It contains, as we have remarked already, a reservoir or tank of water—of course a baptistery—deep and of considerable size.
This singular feature, when taken in conjunction with the great tank or reservoir of the first story and the several smaller tanks or reservoirs discovered in the various corridors and sepulchral chambers—peculiarities and features possessed by no other catacomb—amply justifies the ancient appellation “ad Nymphas,” which no doubt exclusively belongs to the Cemetery of S. Priscilla, and which in several parts seems to preserve a memory of the baptisms of S. Peter.
Over most of the catacombs—certainly over the more important—shortly after the Peace of the Church, basilicas or churches of various dimensions were erected for the accommodation of pilgrims and members of the Roman congregations who desired to visit and to venerate the sanctuaries of the subterranean cemeteries which soon became famous and objects of reverence in the Christian world. The basilica subsequently known as S. Sylvester, which was built over the Cemetery of Priscilla, no doubt before the year 336, has perhaps obtained a greater notoriety than any other of these fourth-century cemetery churches.
Into this basilica, apparently shortly after its erection, were translated many of the bodies of martyrs, whose remains had been in the first instance deposited in the crypts of S. Priscilla beneath. The Pilgrim Itineraries dwell upon this, and especially mention how under the high altar of S. Sylvester two of the martyred sons of S. Felicitas rested—Felix and Philip.